Chapter 1 - Computer Fundamentals

1. Introduction to Computer System

1.1 What is a Computer?

A computer is an electronic device that accepts data as input, processes it according to a set of instructions, stores it when required, and produces useful information as output.

In simple words, a computer

• takes input
• processes it and
• gives output.

Example

Suppose you enter the marks of five students into a computer and ask it to calculate the total and average.

• Input: Marks of the students
• Processing: Addition and calculation of average
• Output: Total marks and average

Basic Terms

Data

Data refers to raw facts and figures that have not yet been processed or organised. Data may consist of numbers, letters, words, symbols, images, audio, or video. .

Real-Life Example

To prepare tea, we need:

• Tea leaves
• Water
• Milk
• Sugar

These ingredients can be considered raw data for preparing tea.

Remember: Raw facts and figures = Data

Information

Information is processed and organised data that gives a meaningful result.

Instruction

An instruction is a command or direction given to a computer to perform a particular operation. A computer cannot decide what to do on its own. It follows instructions supplied by the user or by a program.

Parts of a Computer

A computer system consists of several important parts that work together.

The major parts are:

1. Input Unit
2. Central Processing Unit (CPU)
3. Memory Unit
4. Output Unit
5. Storage Devices

Each part has a specific role in the working of a computer.

Input Unit

The input unit is responsible for accepting data and instructions from the user and sending them to the computer for processing.

Output Unit

An output unit is a hardware component of a computer that receives processed information from the CPU and presents the results to the user in a form that can be understood.

In simple words: The output unit shows or gives us the result after the computer processes the input.

Central Processing Unit (CPU)

The Central Processing Unit (CPU) is the main processing unit of a computer. It processes instructions, performs calculations and controls the activities of other parts of the computer.

The CPU is often called the brain of the computer because it performs the main processing and controls many operations.

Main Parts of CPU

The CPU mainly consists of:

1. Control Unit (CU)
2. Arithmetic and Logic Unit (ALU)
3. Registers
The CPU works closely with the memory unit while processing data

Control Unit (CU)

The Control Unit controls and coordinates the activities of different parts of a computer.

It tells other units what to do, when to do it, and how to do it.

Arithmetic and Logic Unit (ALU)

The Arithmetic and Logic Unit (ALU) is the part of the CPU that performs arithmetic and logical operations.

Arithmetic Operations

It can also perform comparisons such as:

• Greater than
• Less than
• Equal to
• Greater than or equal to
• Less than or equal to

Logical Operations

The ALU can perform operations such as:

• Addition
• Subtraction
• Multiplication
• Division

Registers

Registers are very small and very fast storage locations inside the CPU.

They temporarily hold data, instructions, or intermediate results while the CPU is processing them.

Because registers are located inside the CPU, they can be accessed very quickly.

Example

During a calculation, the CPU may temporarily keep a number or an intermediate result in a register before using it for the next operation.

Memory Unit

The memory unit stores data, instructions and results so that they can be used by the computer.

Memory is an essential part of a computer because the CPU needs access to instructions and data while performing a task.

Example

When you open a program, the instructions and required data are loaded into memory so that the CPU can access them.

Units of Memory

Computer memory is measured in different units.

The commonly used units and relationship are:

1 Byte = 8 bits

1 KB = 1024 Bytes

1 MB = 1024 KB

1 GB = 1024 MB

1 TB = 1024 GB

1 PB = 1024 TB

Types of Memory

Computer memory can broadly be divided into: 1. Primary Memory
2. Secondary Memory

Primary Memory

Primary memory is the memory that can be directly accessed by the CPU.

It stores the data and instructions that are currently being used or are readily available for processing.

Primary memory mainly includes:
• RAM
• ROM
• Cache Memory

RAM

RAM (Random Access Memory) is a type of primary memory used to temporarily store data and instructions that are currently being used by the computer.

RAM is volatile memory, which means that its contents are normally lost when the power is switched off.

Example
When you open a web browser or a word processor, the required data and instructions are loaded into RAM

There are 2 types of RAM

1. Static RAM (SRAM)
2. Dynamic RAM(DRAM)

ROM

ROM (Read Only Memory) is a type of primary memory that stores instructions that are needed for starting or operating the computer.

ROM is non-volatile, so its contents are retained even when the power is switched off.

Example

The firmware required to start a computer is stored in non-volatile memory.

Types of ROM

1. PROM

2.EPROM

3.EEPROM

Cache Memory

Cache memory is a small and very fast memory that helps the CPU access frequently used data and instructions more quickly. It is generally faster than main memory and is located very close to or integrated with the CPU.

Example

If the CPU repeatedly needs certain data, keeping that data in cache can reduce the time required to access it.

Why is Cache Memory Used?

The CPU can process instructions very quickly. If it had to wait for slower memory every time, overall performance would be reduced. Cache helps reduce this delay.

Secondary Memory

Secondary memory is used for long-term storage of data and programs.

It is generally non-volatile, meaning that data remains stored even when the computer is switched off.

Examples

• Hard Disk Drive (HDD)

• Solid State Drive (SSD)

• Pen drive

• Memory card

• CD/DVD

Hardware

Hardware refers to the physical parts of a computer system that can be seen and touched.

Examples

• Keyboard
• Mouse
• Monitor
• CPU cabinet
• Motherboard
• RAM
• Hard disk
• Printer
• Speakers

Hardware cannot perform useful work without appropriate software.

Peripherals

Peripherals are devices connected to a computer that help it perform input, output, storage or communication-related tasks.

Examples

Input peripherals:
• Keyboard
• Mouse
• Scanner
Output peripherals:
• Monitor
• Printer
• Speakers
Storage peripherals:
• Pen drive
• External hard disk
• Memory card

Software

Software is a collection of programs, instructions and related data that tells a computer what to do. Unlike hardware, software cannot be physically touched.

Examples

• Windows
• Linux
• Microsoft Word
• Web browsers
• Media players
• Games

A computer needs both hardware and software to perform useful tasks.

Types of Software

Software can broadly be classified into:

1. System Software
2. Application Software

System Software

System software is software that manages and controls computer hardware and provides a platform for running application software.

Application Software

Application software is designed to help users perform specific tasks.

Application software can be divided into
1. General-purpose software and
2. Special-purpose/custom software.